Heavy smokers have much greater risk of developing dementia

Heavy smoking increases your risk of developing Alzheimer’s disease and vascular dementia at least 157 percent, according to a new study.

A man smoking a cigarette

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In this study as Reuters reports, more than 20,000 men and women were found to have a 157 percent higher risk of getting Alzheimer's disease. For vascular dementia, the second most common form of dementia, these smokers had a 172 percent increased risk. The people in this study were heavy smokers who smoked two or more packs of cigarettes a day.

"Dementia is a disease that crops up in late life, and that becomes clinically apparent, but I think people really need to think about risk factors for it over the life course," said Rachel Whitmer, study co-author and research scientist with Kaiser Permanente Division of Research in Oakland, California.

The study is published in the Archives of Internal Medicine and is sponsored by Kaiser Permanente.

Many other researchers say there is a strong association between smoking and various forms of dementia. However they do not seem to know exactly why this is. People who smoke are more likely to have high blood pressure and cerebral vascular disease, as well as inflammation, Whitmer said. “Smoking may contribute to the damage of brain blood vessels in addition to brain cells”, she said.

This data came from Kaiser Permanente of Northern California The participants were surveyed between 1978 and 1985. At that time, they were between the ages 50 and 60. The diagnoses of dementia among these people were made from 1994 to 2008, The information was gotten from electronic health records.

Researchers found that those who smoked less than two packs of cigarettes a day had a lower but still significant risk. The participants who smoked a half-pack to one pack a day had a 37 percent risk of getting dementia, and those people who smoked between one and two packs a day had a 44 percent association, compared to non-smokers.

This reported risk of dementia among heavy smokers is likely to be underestimated because many of those people will die before they are old enough to develop dementia, the researchers said.

Hepburn noted that there was an ethnically diverse population of both men and women in the study.

"This gives great confidence in saying this kind of heavy smoking has some kind of association – and it looks like a fairly strong association – with the development of the disease," he said.

The study did not look at what happened among people who had quit smoking after the initial survey.

"The brain is part of the body, it’s part of the whole and if you assault parts, it’s going to have an impact on the whole," he said.

The research speaks to what the Alzheimer's Association Maintain Your Brain campaign is promoting: that brain health has a lot to do with overall health.